An experimental study is conducted to investigate the performance of a low-temperature solar Rankine cycle system using working fluid R245fa. The experimental installation consists of a flat plate collector, a throttling valve, a working fluid pump and an air cooled condenser, etc. For the typical weather conditions of October in Tianjin, the experiment results show that the highest heat collecting efficiency of the flat plate collector is about 50%. The measured Rankine cycle efficiency of the system is lower than the theoretical value, due to superheating, subcooling of the working fluid and heat loss of the experimental prototype. Based on the experimental results, an internal heat exchanger is proposed in the solar Rankine cycle system using R245fa, which can obviously improve the Rankine cycle efficiency. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.